Furnace with helical hearth



Jan. 12, 1937. P. FLAJoLlET-BRACQ 2,067,823

FURNAGE WITH HELI'CAL HEARTHv riginall Filed June 1, 1935 sheets-Shogi'.

A Jan. 12, 1937.

P. FLAgolflET-BRACQ FURNACE WITH HELICAL HAEARTHV Original Filed June 21 1935 2l sheets-sheet a Patented Jan. l2, 11937? p 567,823 FUaNAcE Wim Hameln. HEARTH y OFFIC Paul Flajoljietglracd,"Maisonsliamtte, France` Application June 2i., 1935, Serial No. 27,760. Rernewed November 2l,v 1936. -In France July 6,

Furnacesl are already known which are spe cially employed for the roastingof certain ores such as iron pyrites and zincblende, and which comprise for this purpose a hearth'arranged ac- 5V cording to a helix having a certainvnumb'er of spiral turns. l A

The material to be roasted is supplied,v at the top'of the furnace, whilst the air is admitted at the lower part. The material is roasted as it 1,0 descends upon the hearth, and chiefly by the combustion of the sulphur which it` contains, and the speed of the descent isv regulated in such Way that when the material arrives at the lower endof the helical hearth,`it is now entirely 15 roasted. The` gasesrresulting from the combustion are collected at the top of thejfurnace and are employedl in any suitable manner, for linstance for the manufacture of sulphuric acid.

The operating of such furnaces. thus requires an exact regulatingof the rate of descent of the material, in order that the roasting shall be completely effected while the material passes through the furnace. On the other hand, it is very desirable that during the operation the material shall f not be subject to shocks or to violent stirring, in order to avoid the production of dust, as this latter, when drawn along with the gases' of combustion, would represent a great impurity in such gases.

It has already been proposed to assure the descent of the material at the desired speed, by mounting in the furnace at suitable heights, radial arms carried by a common central cylin`- drical chamber, and a suitable mechanism gives 5 to the chamber a general helical displacement, with the same pitch as that of the hearth, and with an amplitude which somewhat exceeds the quotient of the number of spiral turns of the hearth divided by the number of arms employed.

40 For instance, if the spiral hearth extends through four turns, and if the shaft carries four superposed arms, the amplitude of the helical moverment of the shaft carrying these Yarms vshould slightly exceed a complete turn.

Hitherto, the arms thus arranged were provided,`in the interior of the furnace, with one or more radial blades perpendicular to the surface of the hearth and adapted to drive forward, always according to the greatest slope, the mass 50`of material situated in front of them, and the shaft together, with the arms were given at the same timeas the general helical movement above described, a particular movement consisting of a succession of circuits, each of which comprises ,55 the following phases: lifting of the blade above 3 claims; f (ci. 26a- 26)Y the material, fand'la lunit lhelical descent, with the driving forward of the part of the material thus cut off. This method provided for a sectional descent of the material dividedlup into radial portions, andwouldhave been considered as` satisfactory, had 'it not been that the moveT- ments of the shaft and the arms were too complicated to beV obtained in industrial operation with regularity, safety and absence of wear, and also without an excessive consumption cf power. The present `invention relates to improvements by which the gradual descent of the material along' the helicaly hearth is assured by devices effecting much more` simple movements, and hence the mechanism actuating such devices is more suitable for an economical and reliable industrial operating.

In conformity with the invention, each arm which extends into the furnace is provided, not y with a radial blade, but with a certain number of'blades which are staggeredv and are oblique with reference to the direction of the arm, and have contrary directions in pairs. By this means, .the continuous movement of the arms in the material will be sufficient to produce, at the same time as the ldescent of the material, radial movements, towards the center for onei blade, and then towards the periphery for the adjacent blade, and thus each unit part of the i material will be located, after the passage of the arm, in a'somewhatr lower position, but will be practically at the same distance from the axis of the furnace as before.

As the movement of each arm is continuous, the material will not be abruptly stirred up, and will produce no dust. However, the zigzag movement given to each unit part of the material will'v have the effect of displacing it inthe positive sense, as well as relatively to the adjacent unit parts, and thus each time the arm passes along, the material will be overturned as if by plowshares, and will be distributed in the form of helical furrows, thus affording conditions ywhich are particularly adapted toassure the proper roasting.

Thus the movement to be given to the arms is limited aside from the general movement of the cylinder as above disclosed, to the lifting of the blades out of the material at the lowest point of the movement, and to a penetration into the material at the highest point.

In order to comply with these conditions, and according to the invention, the said yblades are secured to the :ends of extensions Which are per- 'the material,A a' unit helical rise, penetration into n pendicular to the arms. On the otherhand, the arms may pivot on their axes, with reference to the cylinder upon which they are mounted in order to release the blades from the layer of material; this pivoting movementl can be obtained at the beginning and the end of the general movement of the cylinder by any suitable mechanical means, and chiefly by the use of stops which are properly located on the path of the rod-and-link gear attached to the arm.

A constructional form of an improved furnace according to the invention is shown by way of example in the accompanying drawings.

Fig. l is an elevational section of the furnace.

Fig. 2 is a plan View of a part of the furnace hearth, showing the scraping arms.

Fig. 3 is an end view of one of the arms.

Fig. 4 is a view of the mechanism of the. furnace, on a larger scale. V

In Fig. l will be recognized the arrangement of a known furnace with spiral hearth, in which I is the hearth itself, comprising, in this particular case, somewhat more than three spirals superposed.

At the upper part of the hearth III are shown at II the conduits supplying the material to be roasted; the discharge of the roasted material and the intake of the air required for the roasting take place at the lower part of the furnace in the region I2, through suitable arranged openings, not shown. f

On the axis of the spiral formed by the hearth Ill, is located a vertical cylindrical chamber I3` provided at suitable heights with radial arms I4 extending upon the whole width of the hearth I0 and adapted for a slight axial pivoting.

As shown in Figs. 2 and 3, each arm I4 carries a certain number, four in the present example, of perpendicular extensions I5, each of which is terminated by a blade I6 which is perpendicular to the surface of the sole I0 and is suitably oblique with reference to the direction of the arm.

The consecutive blades have contrary directions, and on the other hand, the said blades are somewhat displaced, that is, they have an overlapping arrangement.

It will be noted that if such an arm is moved in the direction of the arrow F, following along the slope of the hearth, the action being such that the blades scrape over the surface of the hearth, all of the material which is located at A, for instance, will be driven forward by one of theqblades I6, but owing to the centripetal Obliquity of said blade, the material will be displaced downwardly and also towards the centre according to a line which may be represented by A--B while sliding along the blade. The material thus left at the point B by one of the blades will be collected by the next blade, which has a centrifugal Obliquity and thus causes the material to follow the path E-C and then leaves -the material at the point C.

Thus when the material is met successively by the two blades of the arm, it proceeds upon a path A--C on the line of the greatest inclination of the hearth I0, but the material is not displaced with reference to the axis of the hearth.

It will follow that the movement of the arm rthus arranged will cause a limited descent of the material without changing the general distribution of this material upon the hearth. Each pair of blades leaves behind it a furrow of theI same kind Yas left by the preceding blade.

The axial chamber I3 is pivotally mounted on an upright axle I1 secured to the piston I8 of a hydraulic press whose main body I9, adapted for the vertical upward and downward movement of the piston, is supplied with a suitable liquid by a pump driven by a motor 2I. For

this purpose, the pump is connected by a conduit 22 with the body I9 of the hydraulic press.

However, the axle I1 is surrounded by a hub 23 secured to the cylinder I3, and it is thus adapted to rotate about the said axle. The hub is wound with a cable 24, whose ends are attached at 26-21 to suitable points of a rigid carriage 25.

The said carriage comprises two sliders 28- 29 adapted for displacement on a guide 30, which is oblique and is secured to the main frame with a determined inclination. On the other hand, one of Vthe said sliders, 28 for instance, is engaged in a table 3|, in which it can vmove radially but will partake of yall the vertical V'movements of the table.

The said table rests upon a bearing 32 which can beraised by the hub 23, but without *any axial rotation of the said hub. 'I'he other slider 29 is connected by a link 33 to a guide 34v in which is engaged the end 35 of a pivoted lever35 which is provided with a'weightl 3l and Whose other end is attached toa reversing device 38'controlling the output of the pump 20.

The guide 34 may also be employed for controlling at 39,' various auxiliary devices used with the furnace, and chieily the feeding 'device for the material, not shown.

Each arm I4, whichmay' rotate on -its axis with reference to the cylinder I3, carries at its end which traverses the wall of the cylinder, a crank 4D (Fig. l) which is`connect'ed by a rod 4I to a ring 42 having a lower appendage 43 (Fig. 4) cooperating with a loweri'lxed stop 44.

On the other hand, the said 'appendage cooperates with a spring catch 43 which is mounted on the cylindrical chamber and upon rwhose path is located an upper fixed stop 46.

The operation of the furnace above described is as follows.

Let it be supposed that the furnace is in operation in which case the hearth is provided with material and the latter is being roasted, and also that the parts are in the positions shown in the drawings, the pump 20 delivers liquid into the body, and the piston I8 rises'. y

The general rising movement lof the piston I8 and the chamber I3 due to the delivery of the pump 20 into the body I9, is imparted to the table 3I, and hence the said table will raise the guide 28 of the carriage 25.

As the said carriage, by means of vits guides 2li-29, is guided in the oblique guide 30, it will not only rise but will also be displaced towards the left of Fig. 4, and due to this displacement, a traction will be exerted upon the cable wound on the hub 23, thus rotating the cylinder I3 about the axle I1. 1

'I'he ratio between the rotation and the`lifting of the cylinder is so determined that the pitch of the helical path which it covers will coincide with the pitch of the helicalhearth IU.

In consequence, whether the cylinder rises or descends, the arms I4 will always remain at a constant distance above the surface of the hearth.

However, the movement of the carriage and vthe guide 29 to the left of Fig. 4 will produce, by means of the link 33, adisplacement of the guide 34 to the left, so that the.' Ieverf's' 'will turn's,

about, and under the eiect of the Weight 31, after having passed through the vertical position, it will pivot in the counter-clockwise direction.

This movement displaces, to the end of its stroke, the reversing device 38 controlling the pump 2|, and the pump will no longer deliver liquid into the body I9, but will allow the liquid to leave this body at a determined speed.

In consequence, the piston I8 together with all the parts which it carries will descend under the weight of the cylinder I3, thus reversing the movement of rotation of the cylinder, by the traction eiect of the cable 24.

At the same time, the end of the catch 45 makes contact with the upper xed stop 46, and thus the catch will turn about and will separate from the appendage 43. The arms I4, which are moved by the weight of their extensions I5 and of the blades I6, will pivot slightly on their axes until the blades enter into the material which is spread upon the hearth.

During the whole of the descent, the blades I6 will thus act upon the material, as above disclosed, thus moving it to a limited degree and turning it over.

When the piston I8 and the cylindrical chamber come nearly to the end of their descent, the appendage 43 makes contact with the stop 44, thus holding the said appendage in position, and during the last part of the descent of the said chamber, the catch 45 comes under the said appendage in order to keep it in place.

During this latter movement of descent of the cylindrical chamber with reference to the appendage 43 and the ring 42, the arms I4 will pivot on their axes, and the blades I6 will thus be removed from the layer of material which is located upon the hearth.

At the end of the descent of the piston and of the carriage 25, the guide 34 will operate through the lever 36, the reversing device 38, and the pump now delivers into the body I9 of the press.

The cylinder I3 now rises, while also rotating but as the blades I6 are now released from the material, this latter is not moved back.

At the end of the upward course of the cylinder, the movements will be repeated, as above disclosed, and so on.

Obviously, the invention is not limited to the form of construction above described, and the construction of the apparatus may be modified, Without departing from the spiirt of the invention. Thus the scraping arms may be made hollow and may be cooled by a circulation of air or Water.

I claim:

1. Improvements in furnaces with helical hearth, comprising a cylindrical chamber located within the axis of the helix, arms extending from said chamber and above said hearth, a hydraulic press having said chamber pivotally mounted thereon, means for automatically controlling said press, a fixed oblique guide, a carriage mounted on and guided by said fixed oblique guide, said carriage being raised and lowered by the movements of said chamber, and a cable connected at one end to said carriage and its othen end wound around and connected to said chamber effecting a helical movement of said chamber during the operation of said hydraulic press.

2. Improvements in furnaces with helical hearth, comprising a cylindrical chamber located Within the axis of the helix, arms extending from said chamber and above said hearth, a plurality of blades mounted on each of said arms, a means giving said chamber a vertical movement, a second means giving said chamber a reciprocation during the time said rst means is imparting a complete vertical' movement, and an automatic means for rotating said arms in order to alternately raise and lower said blades according to the position of said chamber.

3. Improvements in furnaces with helical hearth, comprising a cylindrical chamber located Within the axis of the helix, arms extending from said chamber and above said hearth, a hydraulic press having said chamber pivotally mounted thereon, a xed oblique guide, a carriage mounted on and guided by said guide, means connecting said carriage to said chamber and said carriage being thereby raised and lowered by the movements of said chamber, a cable connected at one end to said carriage and its other end wound around and connected to said chamber effecting a helical movement of said chamber during the operation of said hydraulic press and a means for automatically controlling said press, comprising a link connected to said press, a guide operated by said link, a pivoted l lever connected at one end in said guide and having this end weighted, a reversing means 0perated by said lever whenever said chamber is in its uppermost or lowest position, and a pump operated by said reversing means for pumping liquid into said hydraulic press.

PAUL FLAJOLIET-BRACQ. 

